Preterm delivery and other pregnancy-related conditions such as the delivery of low birth weight neonates and/or small for gestational age neonates have serious health, societal, and economic costs. For example, preterm delivery and the delivery of low birth weight neonates and/or small for gestational age neonates can lead to neonatal morbidity, longer stays in the neonatal intensive care unit, and a higher risk of long term morbidities including, for example, cerebral palsy, mental retardation, and learning disabilities.
Administration of steroids such as 17-α-hydroxyprogesterone caproate (“17-HPC” or “HPC”) has been used to reduce the risk of, e.g., preterm birth. HPC has the structure:

Polymorphism is the ability of a substance to crystallize in more than one crystal lattice arrangement. Crystallization, or polymorphism, can influence many aspects of solid state properties of a drug substance. A crystalline substance may differ considerably from an amorphous form, and different crystal modifications of a substance may differ considerably from one another in many respects including solubility, dissolution rate and/or bioavailability. Generally, it is difficult to predict whether or not a given compound will form various crystalline solid state forms. It is even more difficult to predict the physical properties of these crystalline solid state forms. Further, it can be advantageous to have a crystalline form of a therapeutic agent for certain formulations.